Coupling Effects of Braiding Architecture and Thermo‐Oxidative Aging on the Axial Compressive Behavior of Three‐Dimensional Braided Composite Thin‐Walled Tubes

ABSTRACT Three‐dimensional (3‐D) braided composite thin‐wall tube has become an ideal choice for lightweight construction due to its high specific strength and stiffness. However, its long‐term performance under thermo‐oxidative environment remains poorly understood. This study aims to investigate the thermo‐oxidative axial compressive behavior of 3‐D braided carbon fiber/epoxy composite tubes with different braiding angles (15°, 25°, and 35°), layers (2, 3, and 4), and axial yarn configurations. Axial compression tests were performed, and microstructural damage was analyzed using scanning electron microscopy and micro‐CT. The results showed that larger braiding angles and fewer layers led to significant reductions in compressive strength after aging at 180°C, while 3‐D five‐directional (5D) braiding architectures improved initial strength but increased brittleness under prolonged aging. Shear failure with extensive fiber buckling was identified as the predominant failure mechanism. These findings provide insights into the optimization of 3‐D braided composites for use in extreme environments.